Editing Roller coaster (section)

==Safety==
Some sources have shown concern over the ability of roller coasters to cause head trauma and serious injury such as the tearing of axons and damaging of blood vessels.<ref>{{Cite web |date=2023-06-15 |title=The link between roller coasters and headaches |url=https://www.medicalnewstoday.com/articles/headache-after-roller-coaster |access-date=2024-02-07 |website=Medical News Today |language=en}}</ref><ref>{{Cite journal |last1=Kuo |first1=Calvin |last2=Wu |first2=Lyndia C. |last3=Ye |first3=Patrick P. |last4=Laksari |first4=Kaveh |last5=Camarillo |first5=David B. |last6=Kuhl |first6=Ellen |title=Pilot Findings of Brain Displacements and Deformations during Roller Coaster Rides |journal=Journal of Neurotrauma |date=2017 |volume=34 |issue=22 |pages=3198–3205 |doi=10.1089/neu.2016.4893 |pmid=28683585 |pmc=6436029 }}</ref>

=== Safety mechanisms and technology ===
A variety of safety mechanisms protect riders on roller coasters. 

==== Block system ====
Most large roller coasters have the ability to run two or more trains at once. 

The block system prevents these trains from colliding. In this system, the track is divided into two or more sections known as blocks. 

* Only one train is permitted in each block at any given time. 
* There is a section of track at the end of each block where a train can be stopped if necessary. 
** Examples include block brakes, the top of a lift hill (that can stop) and the station (train will not dispatch until the next block is clear).
* Sensors detect when a train passes so that the system's computer is aware of which blocks are occupied. If a train attempts to enter an occupied block, the stopping mechanisms in all blocks are engaged.{{citation needed|date=August 2023}}

==== Seat restraints ====
Seat restraints are used to ensure that riders stay in their seats throughout the ride.

===== Types of restraints =====
{| class="wikitable"
|+
!Type of restraint
!Description
!Pros
!Cons
!Sources
|-
|Over-the-shoulder
|Secures riders' torsos using a harness that is pulled down over the rider before the ride starts. 
|
* Can feel more secure for scared riders
|
* Can cause headbanging
* Can remove some airtime
* Can feel cramped or claustrophobic
|<ref>{{Cite web |title=Over-the-shoulder harness - Coasterpedia - The Amusement Ride Wiki |url=https://coasterpedia.net/wiki/Over-the-shoulder_harness |access-date=2025-05-10 |website=coasterpedia.net |language=en}}</ref>
|-
|Lap bar
|Secures riders' laps using either a bar that's pulled from in front of riders or pulled down from above like over-the-shoulder restraints
|
* More airtime
* No headbanging
* More open feel
|
* Can feel insecure or exposing for scared riders
* Can cause misconceptions that roller coasters with inversions that use lap bars are dangerous
|<ref>{{Cite web |title=Lap bar - Coasterpedia - The Amusement Ride Wiki |url=https://coasterpedia.net/wiki/Lap_bar |access-date=2025-05-10 |website=coasterpedia.net}}</ref>
|-
|Vest
|Similar to over-the-shoulder restraints but uses a vest pulled tightly on the rider's torso to secure them
|
* No headbanging
* Less bulky than over the shoulder restraints
|
* Tight
* Can remove airtime
|<ref>{{Cite web |title=Vest harness - Coasterpedia - The Amusement Ride Wiki |url=https://coasterpedia.net/wiki/Vest_harness |access-date=2025-05-10 |website=coasterpedia.net |language=en}}</ref>
|-
|Seatbelt
|Uses a belt across the rider's waist to secure them, or can be used as a fallback for other restraints
|
* Can be used in conjunction with other restraint types as a fall-back
* Can make scared riders feel more secure when used in conjunction with other restraints
* When used alone is very open and very unrestrictive
|
* Not suitable for most intense rollercoasters
|
|}

===== Restraint locking mechanisms =====
{| class="wikitable"
|+
!Locking mechanism
!Description
!Sources
|-
|Hydraulic
|Uses hydraulic piston and fluid to lock restraints.
When the restraint is pulled down, it forces liquid through a one-way valve. This liquid cannot return and thus the restraint stays closed. When the restraints are unlocked by the ride operator, an electrical signal is sent to another valve, which opens, allowing the fluid to return to the start position and letting the restraint rise.
|<ref>{{Cite book |last=Hoebiger |title=Personal restraint hydraulic lock LE |publisher=Hoebiger |year=2017 |location=Alabama |language=English}}</ref>
|-
|Ratcheting
|Uses a toothed gear and pawl to lock restraints. When the restraint is pulled down, the pawl clicks into the next tooth on the gear. The pawl cannot go in the opposite direction. When the restraint is unlocked by the ride operator, an electrical signal is sent to the pawl which moves it out of the way and lets the restraint go back up.
|<ref>{{Cite web |title=Griffin Schobel - Rollercoaster Restraint System (2019) |url=https://griffinschobel.com/rollercoaster-restraint-system |access-date=2022-05-02 |website=griffinschobel.com |language=en-US}}</ref>
|}
Restraints use proximity sensors to determine if they are locked. If not all of the restraints are locked, the train cannot leave the station.<ref>{{Cite book |last=Väisänen |first=Antti |title=Design of Roller Coasters |publisher=Aalto University School of Engineering |year=2018 |location=Espoo, Finland |pages=11 |language=English}}</ref>

==== Braking systems ====
Braking systems such as pivoting pawls are used on the bottom of the train and on the inclined lift hill. While the train goes up the lift hill, it is pulled by a chain. The pawl moves over bumps that are separated closely apart. In the event that the train ever becomes disconnected from the chain, the anti roll-back system will engage and it will fall back into the nearest downhill stop preventing the train from falling down the lift hill.<ref>{{Cite patent|number=US5715756A|title=Ride attraction anti-roll back system|gdate=1998-02-10|invent1=Weigand|invent2=Black|invent3=Drobnis|inventor1-first=Frank K.|inventor2-first=Alan|inventor3-first=Nick|url=https://patents.google.com/patent/US5715756A/en}}</ref>

==== Programmable logic controller ====
Another key to safety is the [[programmable logic controller]], an essential component of a roller coaster's computer system. Multiple controllers work together to detect faults associated with operation and automate decisions to engage various elements (e.g. lift, brakes, etc.). Periodic maintenance and visual inspection by ride engineers are also important to verify that structures and materials are within expected wear tolerances and functioning correctly. Effective operating procedures further enhance safety.<ref>[https://www.hse.gov.uk/pubns/books/hsg175.htm Fairgrounds and amusement parks: Guidance on safe practice]. ''Health and Safety Executive''. November 2017. Retrieved 7 March 2023.</ref>

=== Roller coaster design and statistics ===
Roller coaster design is another important aspect that requires a working knowledge of [[Kinematics|basic physics]] to enhance ride comfort and avoid harmful strain to the rider. Ride designers must carefully analyze the movement a ride subjects its riders to, ensuring it is within a reasonable tolerance. The human body needs sufficient time to react to sudden changes in force in order to control muscle tension and avoid harmful consequences such as [[Whiplash (medicine)|whiplash]]. Designers typically stay in the range of {{cvt|4|to|6|g-force|sigfig=1}} as a maximum for positive g-force acceleration, which increases the feeling of weight and pushes riders downward into their seat. For negative g-force, or the feeling of weightlessness, the target is {{cvt|1.5|to|2|g-force}} as a maximum. These fall into a range considered safe to a majority of the population. Lateral acceleration is also typically kept under {{cvt|2|g-force}} using various techniques including the banking of curves.<ref>{{Cite news |title=CoasterForce |url=https://coasterforce.com/physics/ |access-date=9 May 2022 |website=CoasterForce}}</ref>

Wheels are a critical part in rollercoaster design. The purpose of wheels is to keep the train on the track and to prevent it from flying off. A majority of roller coaster wheels are made from polyurethane. There are three kinds of roller coaster wheels which include road wheels, side friction wheels, and up-stop wheels. Road wheels ride on top of the track. Side friction wheels ride on the side of the track to keep the train on the track throughout turns. Up-stop wheels ride below the track and prevent the train from lifting off the track.<ref>{{Cite book |last=Hunt |first=Kristen |title=Design Analysis of Roller Coasters |publisher=Worcester Polytechnic Institute |date=May 2018 |location=Worcester, MA |pages=11 |language=English}}</ref>

Roller coasters are statistically very safe when compared to other activities, but despite all the safety measures in place, [[Amusement park accidents|accidents]] still occur. The [[International Association of Amusement Parks and Attractions]] (IAAPA) reports that a rider has one chance in 15.5 million of being injured on a ride. Also, "In a typical year, more than 385 million guests enjoyed in excess of 1.7 billion rides at approximately 400 North American fixed-site facilities". IAAPA is required to report annual ride incidents to the National Safety Council.<ref>{{Cite news |last=National Safety Council |date=August 2021 |title=North America Fixed-Site Amusement Ride Injury Survey, 2020 Update |pages=1–14 |work=International Association of Amusement Parks and Attractions Orlando, FL}}</ref><ref>{{Cite web |title=Amusement Ride Safety {{!}} IAAPA |url=https://www.iaapa.org/safety-security/amusement-ride-safety |access-date=2022-05-02 |website=www.iaapa.org |language=en}}</ref>